Plated metal and the manufacture thereof



Dec. 17, 1935. E. H. DAVIGNON K 2,024,150

PLATED METAL AND THE MANUFACTURE THEREOF File@ July 51, 1953 3 :gi n PRfC/OUJ METAL. A "w `oLLvEA1 f K ELEcrEoPLAr-Eo LAYER FIG. 2.

PREC/'0&5 METAL SoLoE/e yBgm/v6 MErAL L FIG. 3.

4 PEEc/ous MEI-AL f ne/mv@ METAL BASE METALV Patented Dec. 17, 1935` UNITED STATES PATENT OFFICE I PLATED METAL AND THE MANUFACTURE THEREOF y Application July 31, 1933, Serial No. 682,959

2 Claims.

This invention relates to plated metal and the manufacture thereof, and with regard to certain more specific features, to metal wherein a relatively cheap base metal of non-tarnishing character is plated with a thin film of a relatively precious metal.

Among the several objects of the invention may be noted the provision of a plated metal stock for jewelry and the like wherein the base` metal is of non-tarnishing character, such as stainless steel, and wherein the surface metal ls relatively precious, such as gold, the two being bound together firmly and with uniform cohesion along their line of jointure, the precious metal layer being formed by a process of mechanical attenuation in distinction to an electroplating or electro-chemical deposition process; the provision of a mechanically plated metal of the class described wherein the backing metal is not ordinarily suited to soldering or welding or the like; and the provision of a plated metal and a method of manufacturing the same which is relatively simple to carry out. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, steps and .sequence of steps, features of construction and synthesis, and arrangements of parts, which will be exemplified in the structures and processes hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing,.in which arel illustrated several of various possible embodiments of the invention,

Fig. 1 is a diagrammatic cross section of a composite bar or block which may be used in carrying out the present invention;

Fig. 2 is a diagrammatic cross section of a plated stock material; and, y

Fig. 3 is a diagrammatic cross section of a block similar to Fig. 1, which may also be used in carrying out the present invention.

Similar reference characters indicate corresponding parts throughout the several views of the drawing.

In Victor D. Davignon Patents Nos. 1,571,540 and 1,571,541 are shown plated metals of the class herein generally concerned. In the production of plated metal of this class it is customary to start with a block or bar of cheaper base metal, such as for example, brass or nickel silver, upon which is placed a thin sheet of precious metal, such as gold, with an interposed thin sheet of fusible solder, such as silver solder. The precious metal is then fused to the base metal in a soldering furnace and the blank comprising this composite block or bar is subjected to a rolling, drawing, or other mechanical process 5 designed to reduce the aggregate thickness of the unitary piece, such process being carried to a point where the precious metal is left as a thin surface coating on the usually relatively thick base metal body.

Mechanically fabricated plated work is in great demand and is much more durable and wear-resisting than that produced by the electro-plating process. In the production of the more inexpensive grades of plated wear, however, mechanical attenuation by rolling or otherwise is often carried to the point where the surface coating of precious metal is not only reduced to a very thin film, but tends to become distributed over the base metal surface in fine particles and 20 apparently separated at imperceptible intervals, or more or less comingled at places with particles from the soft underlying base metal into which it has been worked.

In the production of such inexpensive gold or other precious metal rolled plate, a point is soon reached where the product is susceptible to dis'- coloration, oxidation, or other similar eiects due to the exposure of the base metal through the precious metal coating. rIhis characteristic 30 tarnishability renders the product less available for use in jewelry manufacture and other similar purposes.

`The aforesaid Davlgnon patents present one method of overcoming this difficulty, which con- 35 sists in interposing a layer of non-tarnishing vmetal between the precious metal and the base metal. The present invention likewise solves the ydifficulty noted, but by using as a base metal, such a metal as is non-tarnishing. For example, stainless steel may be used. Stainless iron is herein considered to be a variety of stainless steel, and may also be used.

The precious metal layers cannot be amxed to stainless steel by the ordinary method of soldering, however, because of the tendency of such stainless steel to form refractory oxides on the surface when a piece is heated for the soldering operation, these oxides preventing the securing Y of a goed weld.

The use of stainless steel as a base' metal oiers considerable advantages over other base metals, both tarnishing and readily weldable non-tarnishing metals. For example, plated stainless steel stock may be cut or blanked into small shapes having unprotected edges or ends, and such edges or ends will not themselves tarnish. Such pieces are used, for example, inwatchk bracelets and other pieces. of jewelry on which the edges and ends are exposed to the tarnishing effects of perspiration from the body of the wearer. Stainless steel offers a considerably higher degree of nontarnishability than metals such as nickel silvers and the like heretofore used as stainless base metals. Nickel and Monel metal, which have also been used heretofore as non-tarnishing metals, are disadvantageous in some instances because of their magnetic characteristics. Stainless steel, it

will be understood, may be made magnetic or nonf magnetic, as the occasion demands. l

It is not intended that this invention shall be limited to the use of stainless steel as a base metal, or to the use of only preciousy metals in the surface layer. In the broader aspect, the invention concerns mechanical plating of any metal on to a base metal which in the normal course of events forms refractory oxides inhibiting the securing of a good bond.

To illustrate one method of carrying out the invention, a block or bar of the desired base metal, for example, stainless steel, is first provided. This bar is rlrst properly cleaned, either mechanically or chemically or both, after which a primary coating of nickel, or other suitable metal, is electrolytically applied to the clean surface on which it is desired to plate the gold or other precious metal.

The purpose of the primary coating is to protect the clean surface of the base metal bar fromy the attack of substances or gases which would form the undesirable compounds such as the refractory oxides mentioned above, at the high heats necessary for soldering or welding. The metal of the primary coating may be any one of a large number, but it is of course desirable that such a metal does not itself exhibit the same character of forming refractory oxides. For examples, some of the metals which have been found suitable for this purpose are nickel, copper, gold. silver and others.

It has in some instances been found desirable that the primary coating be made up of two layers electrolytically applied in sequence. For example, in using stainless steel as a base member, a coating of nickel .002 of an inch thick with a flashing of copper has been found to give good results.

In addition to the protection of the base metal during the soldering or welding operation, the

primary coating eifects a more profound diffusion,

that is, a better interpenetration of the metals at their joining surfaces, and hence a better joint.

Following the application of the primary coating, the surface is again cleaned and a sheet of solder such as silver solder is laid in place, followed by a sheet of gold or such other precious metal as is to be used for the plating operation. The sheet of solder may be of any desired thickness, but in the illustrative example a sheet .002 of an inch thick will suffice. The thickness of the precious metal sheet will depend on the quality of the plate desired, and in the illustrative example might vary from .006 to .090 of an inch or might even be outside these limits. The assembled parts-are then clamped together or otherwise placed under pressure and placed in a soldering furnace and fused or welded together.

It is also possible to use direct welding without any solder, the heat being sufficient to cause interpenetration of the primary electroplated metal and the basef metal on the one hand, and the precious metal and the primary electroplated metal on the other hand, to secure a good joint.

The ultimate block is then subjected to the usual mechanical operation heretofore character- 5 ized, such, for example, as a. succession of rolling actions, to produce thin plated metal sheets, or a drawing process or a combination of rolling and drawing to produce seamless wires, rods, or tubes.

This product block is illustrated in Fig. l, in 10 which numeral I indicates the base metal, numeral 2 indicates the primary electroplated layer, numeral 3 indicates the solder layer, and numeral 4 indicates the precious metal layer.

It will be apparent that the procedure above 15 described may also be carried out on the other side of the block of the base metal in case it is desired to produce a product which is plated on both of its sides.

If it is desirable to produce a very cheap form of plate, a composite block such as that illustrated in Fig. 2 may first be prepared. This comprises the usual precious metal layer 4, which is secured by a solder layer 3 to a block of backing metal 5. The backing metal 5 is preferably non-tarnishing and readily workable. Nickel, for example, is suitable. This composite block, as illustrated in Fig. 2, may then be rolled to a certain thinness, and cut into smaller portions and each portion assembled as a unitary layer together with other layers as illustrated in Fig. 3. Referring to Fig. 3, it will be seen that the top three layers comprise the metal prepared as in Fig. 2. Between this composite metal and the base metal I, which may be stainless steel for example, are provided, first, the primary electroplated layer 2, then a solder layer 3, then a layer 6, preferably of the same backing metal as the metal in layer 5, and finally another solder layer 3. The layer 6 is preferably welded or soldered to the base metal l (with its primary layer 2 in position) prior to assembly with the composite metal layer of Fig. 2. The purpose of this intermediate operation and layer is to render it unnecessary to heat the gold layer to 45 the temperature necessary to fuse the nickel backing layer to the stainless steel base metal, this temperature being higher than the melting point of gold.

From the above it will be seen that a method has been provided for mechanically plating precious or other metals onto a base metal of a. recalcitrant nature, without occasioning formation of refractory oxides which would interfere with the securing of a good weld. It is also obvious that this method may be employed in plating a recalcitrant metal on a non-recalcitrant base metal or even on a recalcitrant base metal. The weld secured by carrying out the present invention is of sufficient strength to withstand mechanical operations, such as rolling and drawing to the required extent.

In View of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions and compositions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. The method of manufacturing finely atten- 75 hated, plated, jewelry stock metal which comprises cleaning the surface of a base metal layer of stainless steel, electrodepositing a. thin layer of nickel on said cleaned surface, placing a layer of soldering material and a layer of precious metal in the order named on said electrodeposited layer, clamping the assembly together and subjecting it to heat, whereby the assembly is securely soldered together, and thereafter rolling the assembled metals progressively until the iinely attenuated stock is obtained.

2. A finely attenuated plated jewelry stock comprising a base metal backing of stainless steel, an electroplated layer of nickel upon one surface of said stainless steel, and a finely attenuated layer of precious metal soldered to said layer of nickel.

ERMAND HENRY DAVIGNON. 

